British shoppers are ignorant about the conditions in which the pigs that supply much of their bacon and pork are kept, according to Jamie Oliver, as the TV chef launches a new campaign.

Oliver and the RSPCA will call on the EU to set tougher minimum welfare standards for farmers and legislate on more honest labelling about how their animals are reared.

The RSPCA hopes Oliver's programme, Jamie Saves Our Bacon – to be screened by Channel 4 this month – will help to do for pigs what it and another celebrity chef, Hugh Fearnley-Whittingstall, did for chickens last year. Their campaigns led to significant increases in sales of poultry raised to higher welfare standards.

Britain is only about 25% self-sufficient in bacon and 70% in pork, meaning it imports large quantities of pig meat, which farmers in the UK complain comes from animals generally raised in worse and more intensive indoor conditions, including in much of the EU. But the RSPCA's Julia Wrathall said even in this country "a significant number" of the 9 million animals reared for meat each year "are living out their lives in unacceptable conditions".

Wrathall called on supermarkets and other retailers to voluntarily develop labels that gave clear explanations about how pigs were farmed – including free range, outdoor bred or outdoor reared – before any changes that might be agreed by Brussels after an EU review of welfare and labelling rules. A survey of more than 1,000 adults for the charity suggested just 2% could understand such terms, despite animal welfare seeming a strong factor in consumers' buying decisions.

Wrathall, head of farm animal science at the charity, said: "It may come as a surprise but there are actually no industry-wide agreed definitions when it comes to labelling, in complete contrast to eggs and chickens, that do have legal definitions at EU level for terms such as 'free range'. We need clearer labelling, and under a system which makes sense to everyone."

Oliver endorsed the calls, "particularly as the variation in pig welfare across Europe and the world is so diverse. How many people outside of the industry know the difference between outdoor-bred and outdoor-reared, for example? Not many," he said.

The RSPCA said: "Although the perception is that keeping livestock outside is best for welfare, it does not always hold true. Free range systems in which pigs are kept throughout their lives in paddocks do ensure animals have freedom to move around and express natural behaviours."

However, the term "outdoor bred", while it seemed to send the right messages to consumers, was usually used to label pork from pigs that had spent only the first three or four weeks of their lives in free-range systems. While their mothers might stay outside all their breeding lives, the piglets were usually moved into indoor systems that could vary considerably in welfare standards for the rest of their lives, which could be another four to five months.

"Outdoor reared" pigs, though comparatively rarer, could usually have access to outdoors for up to 10 weeks before being moved indoors.

A spokesman for Oliver's programme, to be screened on January 29, said it would cover pig rearing from insemination to slaughter and the plate, with a detailed consideration of welfare issues including tail docking, sow stalls and farrowing crates. The chef would also warn consumers that not all pork claiming to be British food was reared here, a practice that the environment secretary, Hilary Benn, said last week must end, despite current EU laws allowing such labelling provided the food had undergone its last significant processing in this country.

"He is very supportive of British farmers. There is no sense of this being an exposé. He is not wagging his finger at all but saying 'I am giving you this information so you can make your own decisions.'"

BPEX, the British pig industry body, agreed there needed to be "clear, honest and unambiguous labelling". But Animal Aid, another campaigning charity, which advocates vegetarian and vegan lifestyles, said last week that conditions on English pig farms were still "appalling", with barren, overcrowded pens. The only answer was to boycott pork altogether, it said.